Cutter bar

ABSTRACT

A cutter bar for a mineral cutting machine such as a coal cutter which bar is provided with a tapered body portion formed from a pair of oppositely facing elongated support channel members of Ushaped cross section secured and spaced apart in back toward back relationship by a plurality of spacer blocks rigidly secured therebetween and guideways formed of paired, channel-forming, one piece guide members of Z cross section having respective leg portions inserted in the support channels to form guideways of Ushaped cross section for a cutter chain having a link with leg portions to be inserted in the guideways and gibs on the ends of said leg portions to be received in gib raceways formed in the inside surfaces of the guide members adjacent to the bottom surfaces of the guideways.

United States Patent I1 1 Mitchell CUTTER BAR [76] Inventor: Ralph W. Mitchell, P. O. Box 6115,

Franklin, Pa. 16323 [22] Filed: June 29, 1971 [21] Appl. No.: 157,940

[52] US. Cl. 299/82 [51] Int. Cl. E2lc 25/3Q [58] Field of Search 299/82-84; 143/32 H [56] References Cited UNITED STATES PATENTS 3,384,417 5/1968 Mylewski 299/82 2,561,657 7/1951 Fu1ke 299/84 Primary Examiner-Ernest Purser Attorney-E. Wallace Breisch June 26, 1973 [57 ABSTRACT A cutter bar for a mineral cutting machine such as a coal cutter which bar is provided with a tapered body portion formed from a pair of oppositely facing elongated support channel members of U-shaped cross section secured and spaced apart in back toward back relationship by a plurality of spacer blocks rigidly secured therebetween and guideways formed of paired, channel-forming, one piece guide members of Z cross section having respective leg portions inserted in the support channels to form guideways of U-shaped cross section for a cutter chain having a link with leg portions to be inserted in the guideways and gibs on the ends of said leg portions to be received in gib raceways formed in the inside surfaces of the guide members adjacent to the bottom surfaces of the guideways.

24 n if 20 /2 /4 CUTTER BAR BACKGROUND OF THE INVENTION Cutter bars of the prior art presently in use have commonly been made in a rectangular shape with a curved leading end and a sprocket mounted at the rearward end thereof with the size of the leading end and the distance between the parallel portions of chainbeing dedue to the above considerations would give a bar having too great a width between chains or more particularly when a faster speed such as 700 feet per minute was desired bars of the common width were used but with curved guideways popularly known as bell mouth guideways to line up with the larger sized sprocket without increasing the width of the bar. It has been found that these bell mouth guideways particularly on the tension side of the chain wear out very rapidly because the guideways are maintaining a curve in the chain against the tension on the chain tending to straighten it out with resultant high rates of wear and loss of power through excessive friction.

The taper applied to the cutter bar of the present invention provides for a bigger sprocket aligned with the guideways while maintaining a smaller width at the leading end of the bar. Since it is desirable that the bar be narrow in its dimension from chain to chain for superior maneuverability, the taper feature of this bar providing for a large sprocket with straight guideways and a narrow leading end has been found to satisfy the above described desire for a high speed chain and a maneuverable bar.

In like manner the prior art cutter bars presently known to the inventor of the instant cutter bar were provided with guideways removable from the body of the cutter bar in various ways. Some of the removable guideways were one piece structures of U-shaped cross section such as those shown and described in US. Pat. No. 3,550,962 (Goodrich) but it is to be noted that the fastening means for those guideways were inserted through openings in one of the inside surfaces of the U- shaped guideways and in such position were generally inaccessible to either inspection or removal and replacement and if accidentally loosened could cause damage to the chain since if the cap screws worked out of their places they would be in interference with the chain while it was running. US. Pat. No. 2,304,505 (Morrow) shows paired, channeled forming, one piece guide members of Z-cross sections similar to those of this invention except that the guideways of Morrow are provided with small hardened wear plates attached to the channel forming members as by bolts or rivets through interior surfaces and again the disadvantage of securing members through the inner surfaces is present as well as the small size of the wear plate members which when worn to any great extent tend to tear loose and break up with disastrous results not found in the completely one piece paired guideway members of applicants invention. Furthermore the Morrow structure does not provide for insertion of the respective guide member leg portions in a one piece support channel such as that provided by applicants invention and of great utility in providing a simple accurate construction of a unitary support channel member closely receiving the guide members with a fit suitable for clamping action on the guide members.

Thus, the cutting bar of applicants invention provides simple one piece support channels low in cost, easily machined, and of high strength for clamping simple Z-bar two piece guide members with no small wear plates to tear loose and wear through. With such guide members there is no possible wear on the body of the bar and with the fastenings through the extended legs of the guide members no insertion of fastenings from inside the channel is necessary and there are no rivets or bolts through any wear surface of the guide members. As a result no rivets or bolts can be worn by the chain, the bolts are easily accessible for replacement and visible for inspection and since only bolting is involved all of the guides are replaceable underground and the guide members are selectively replaceable when some of them wear faster than the other guides and the nose shoe and head plates are separately replaceable which is of advantage since the head members, particularly the nose shoe, wear much more rapidly than the straight guide members.

The above objects and advantages of the invention herein set forth will be more readily appreciated and understood upon consideration of the following description and drawings in which:

FIG. I is a top plan view, partly in section, of a cutter bar constructed according to the principles of this invention in the usual position for undercutting a portion of a coal vein;

FIG. 2 is a side elevational view of the cutter bar of FIG. 1;

FIG. 3 is a sectional view of the cutter bar of FIG. 1 taken substantially on line 3-3 of FIG. 1 looking in the direction indicated by the arrows;

FIG. 4 is a side elevational view of a cutter bar similar to that of FIG. 1 constructed according to the principles of this invention and embodying a variation in the positioning of guide members and in use of a solid nose shoe in place of an idler sprocket;

FIG. 5 is an enlarged sectional view of a portion of the cutter bar of FIG. 1 showing a portion of a cutter chain link inserted therein;

FIG. 6 is an enlarged fragmentary partially sectional view of the cutter bar of FIG. 1 showing the sprocket arrangement;

FIG. 7 is an enlarged section taken substantially on line7-7 of FIG. 4 showing the construction of a shoe type cutter head nose;

FIG. 8 is a sectional view taken substantially on line 8-8 of FIG. 7.

DESCRIPTION In FIG. I there is shown a cutter bar generally indicated at 10 constructed according to the principles of this invention made up of a basic bar body 12 best seen in FIG. 3, comprised of a pair of elongated, oppositely facing members of U-shaped cross section hereinafter identified as support channel members 14 and 16, right and left hand members respectively since as viewed in FIG. 1 the forward end of the bar is to the right, the right hand edge of the bar is toward the bottom and the left hand edge toward the top of the page.'The support channel members 14 and 16 are spaced apart and rigidly secured to each other by a plurality of spacer blocks 18 secured to the channel members 14 and 16 at various points along the length thereof as by welding or other rigid attachment. It is to be noted that while the support channel members 14 and 16 appear to be substantially parallel they do in fact form a tapering assembly wherein the taper is controlled by the desired amount of difference in sprocket size between the drive sprocket at the left normally larger and the idler sprocket at the right normally smaller and for example on an 11 foot bar the taper would amount to as much as two inches from the rear of the bar to the forward end or from left to right as viewed in FIG. 1.

As best seen in FIG. 3 each of the support channel members 14 and 16 is an elongated bar of rectangular outline and cross section having in the outwardly facing side thereof a channel 20 in which is closely received the leg portions 23 of a pair of guide members 22 of substantially Z-shaped cross section. As best seen in FIG. 2 there are five pairs of same length guide members 22 on the near side of the bar plus a shorter pair 22 near the right hand end of the bar and there is a similar arrangement on the far side of the bar 10 best seen in FIG. 3 each five pairs of guide members 22 form a substantially U-shaped guideway 24 facing outwardly from a side of the bar 10 along substantially the full length thereof. Adjacent the bottom surface of the guideways 24 is a pair of laterally extending grooves 26 forming raceways along the full length of guide members 22 for the slidable receiption of gibs 30 (see FIG. 5) present on the bottom end of downwardly extending leg portions 32 of the links 29 of a suitable cutter chain such as that described in copending application Ser. No. 158,037, filed June 29, 1971 which application is assigned to the same assignee as is the instant application. The outermost edges or lip surfaces of the guide members 14 and 16 form support surfaces 28 for the upper gibs 34 of the chain links so that as the chain is driven in circulation about the bar 10 inward pressure on the links is slidably absorbed by the gibs 34 resting on the edges 28 and outward forces tending to move the links 29 away from the bar 10 will be absorbed by the upper surfaces of the gibs 30 slidably contacting the downward facing surfaces of the raceways 26 as seen in FIG. 5.

At the forward end of the cutter bar 10, to the right hand side as seen in FIGS. 1 and 2, the cutter bar 10 is completed by an elongated spacer member 19 best seen in FIG. 6 placed between and rigidly secured to the inner surfaces of the support channels 14 and 16 as by welding to complete the slightly tapered, substantially rectangular, basic bar 12. Rigidly but removably secured on each side of the long spacer member 19 by a plurality of threaded fasteners such as bolts and nuts 36 is a pair of forwardly extending, semi-circular ended, flat plate members or head plates 38. The head plates 38 are spaced apart by, the rigidly secured to, a cylindrical spacer 40 coaxial with respect to the semicircular end portions of the spacers 38 and removably secured by a plurality of threaded fasteners such as four cap screws 42. Suitably journaled for rotation about the spacer 40 is an idler sprocket 44 of the correct pitch and number of teeth to provide motion reversal for the cutter chain to be used with this apparatus and proper guidance and run spacing to match up with the raceways 26. The diameter of the inner tooth root circle of sprocket 44 is substantially equal to the distance between the bottom or proximate (nearest together) surfaces of the raceways 26 on opposite sides of the forward end of the basic bar 12.

Formed in the inner surface of each of the head plates 38 is an arcuate raceway 46 having end portions located in juxtaposition to the end portions of the raceways 26 of the guide members 22 or 22' on the left and right hand sides of the forward end portion of the basic bar 12. It is to be noted that the raceway 46 has a broad central portion tapering down to ends of approximately the same width as the raceways 26 so that the gibs on the links 29 being of considerable length along the raceway will have room to make the turn without binding in the raceway 46. An entirely similar raceway is best seen in FIG. 7 and identified therein as raceway 56 for use in a second embodiment of the bar of this invention.

In FIG. 6 there is shown the two end portions of the cutter bar 10 and attached to the rearward end of the bar 10 are shown a mounting bracket 60 pivotally connected to a forward extending frame member 62 and gear case 61 of a coal cutting machine (not otherwise shown) of the type on which a cutter bar such as cutter bar 10 would be mounted. Also mounted on the gear case 61 and rotatable thereby about the same axis as the bar 10, is a drive sprocket 64 of a suitable size and pitch and suitably powered to drive a cutter chain at the desired speed, for example, 700 feet per minute. The size of the drive sprocket 64 of course determines the width of the bar 10 at its rearward end with the diameter of the tooth root inner circle of sprocket 64 being substantially equal to the distance between the rearward ends of the bottom or proximate surfaces of the raceways 26 on opposite sides of the rearward end of the basic bar 12. The raceways 26 are slightly bell mouthed to accommodate variations in the position of the chain as it leaves the left hand raceway at the top as seen in FIG. 6 and after being pulled around the drive sprocket 64 re-enters the raceways 26 on the right hand side of the bar 10. The gibs 30 of the links 29 having entered the raceways 26 are constrained thereby and travel along the raceways 26, through the raceways 46 and with reversal of direction, along the raceways 26 on the left hand side of the bar emerging therefrom to again be pulled around the drive sprocket 64 in a manner well known in the art.

In FIG. 4 there is shown a cutter bar generally indicated at 50 entirely similar to the cutter bar 10 hereinabove described excepting only for the forward end which is provided with a nose shoe type of cutter head best seen in FIGS. 7 and 8 and the arrangement of guide members 22 and 22'. In FIG. 8 it will be seen that the basic bar 12 as above described has the elongated spacer l9 separating and rigidly secured to head plates 48 entirely similar to the head plates 38 of the cutter bar 10 of the first embodiment excepting only that the head plates 48 are separated by and removably connected to a nose shoe 52 of a thickness suitable to match the spacer 19 and of a peripheral shape to mate with the inside surface of the raceway 56 to provide the internal guidance and motion reversal necessary for the circulation of the chain which, in the bar 10 is accomplished by the idler sprocket 44. The radius of the nose portion of shoe 52 is substantially less than one-half the distance between the forward ends of the proximate surfaces of guideways 26 on opposite sides of the nose end of the bar. It is to be noted that the head plates 48 and the nose shoe 52 are readily replaceable underground as there is no welding or riveting necessary in this operation. It is further to be noted that the nose shoe 52 which is the member most rapidly worn out in operation of such a cutter bar can be replaced without even removing the head plates 48 from the bar simply by removing a pair of bolts and nuts indicated at 54 and driving the nose shoe 52 out of its clamped position between the head plates 48, followed by insertion of a new nose shoe 52.

The ability to so readily replace the nose shoe 52 is of considerable importance since as hereinbefore stated it is the most rapidly wearing member of the cutter bar and if replaced before too badly worn will prevent the head plates 48 from becoming badly enough worn to need replacing at the time the shoe is replaced.

it is to be particularly noted that with the guideway sections 22 and 22 removably clamped into place by threaded fasteners it is possible to progressively rebuild the bar in the most worn portions completely underground and to whatever extent is made necessary by the particular amount of wear present at a given time.

Referring again to FIG. 4 it is to be seen that in the case of the bar 50 the standard length guide member 22 is used as the upper rear guide member (to the left as seen in FIG. 4) and is followed by standard length guide members 22 shown as four additional members and finished with a short member 22' at the forward end of the bar 50, while the lower guide members as seen in FIG. 4 begin at the left hand or rearward end of the bar 50 with a short guide member 22 and thereinafter incorporate 5 standard length members 22 with the result that the gaps between the guide members 22 and/or 22 on either side of the bar 50 are mismatched by approximately one-half the length of the individual guide members so that the links 20 traveling through the guides 26 are always supported even though passing one of the gaps on one side or the other of the guideway 24. It has been found that this alternation of the gaps between the guide members considerably reduces the noise of the chain crossing the gaps and it is believed will add significantly to the working life of a bar on which such an arrangement of guide members 22 and 22' is used.

It is to be noted that although the drive sprocket 64 is shown as having six teeth while the idler sprocket 44 is provided with five teeth which difference in size is made possible by the taper of the basic bar there is no reason why this exact number of teeth need be used as for instance seven teeth on the drive sprocket and six teeth on the idler sprocket might well be the desired sizes under certain circumstances. Nor is it necessary that the sprockets differ in size by a single tooth as a greater difference in size accompanied with a greater amount of taper is contemplated as a useful variation of the above described structure and entirely within the scope of the present invention.

It is to be appreciated that with the simple Z-bar paired guide members 22, the head plates 38 or 48 and nose shoe 52 providing the wear surfaces of the bar it is possible to use the kind of steel best suited for resisting abrasion and shock loading. For example the carburizing steel with deeply carburized wear surfaces.

It is still further to be noted that although the support channels 14 and 16 are shown as being formed of a single piece of metal such as a bar of steel it is entirely possible that such support channels could be formed by welding together a pair of heavy steel angles followed by suitable machining to form the unitary support channel structure necessary for the practice of the present invention.

Preferred embodiments of the present invention having hereinabove been described it is to be realized that variations in the structure are expected and envisioned as being within the scope of the present invention. It is therefore respectfully requested that the present invention be interpreted as broadly as possible being limited only by the scope of the appended claims.

What is claimed is:

1. An elongated rigid cutter bar body comprising: a pair of one piece elongated channel members; retaining means extending between at least portions of said channel members to maintain said channel members in spaced relationship with respect to one another; continuously longitudinally extending oppositely outwardly facing slots in respective outer sides of said channel members; and said slots being adapted to releasably retain a mounting portion of a chain guide member therein.

2. A cutter bar body as specified in claim 1 wherein said spaced relationship of said channel members is convergently tapering towards only one end thereof to form a tapering bar body.

3. A cutter bar incorporating a cutter bar body as specified in claim 1 wherein the taper of said tapered body matches the difference in size between a drive sprocket mounted at one end of said body and a smaller idler sprocket mounted at the other end of said body.

4. A cutter bar as specified in claim 3 wherein said drive sprocket has six teeth and said idler sprocket has five teeth.

5. A cutter bar incorporating a cutter bar body as specified in claim 1 having chain guide assemblies at each side of said cutter bar body, each of said chain guide assemblies consisting of two guide members each including a pair of laterally spaced oppositely extending elongated portions with corresponding ones of said elongated portions being closely received within the one of said slots cooperative therewith, and means extending across said slots and through said ones of said elongated portions respectively to rigidly support said guide members with respect to said cutter bar body.

6. A cutter bar as specified in claim 5 wherein said paired guide members are longitudinally offset so that gaps between guide members along one side of a portion of said cutter bar body are longitudinally spaced from gaps between guide members along the other side of said portion of said cutter bar body.

7. A cutter bar as specified in claim 5 wherein the proximate guide surfacesof said guide assemblies on opposite sides of said bar are separated at one end of said bar by a distance substantially equal to the diameter of the inner tooth rot circle of a drive sprocket mounted at one end of said bar and said proximate guide surfaces at the other end of said bar are separated by a distance substantially less than said diameter.

8. A cutter bar as specified in claim 7 comprising a nose shoe at said other end of said bar, said nose shoe providing an arcuate guide surface having a nose radius substantially less than one half the distance between said proximate guide surfaces at said other end.

9. A cutter bar as specified in claim 7 wherein said distance substantially less than said drive sprocket diameter is substantially equal to the diameter of the inner tooth root circle of an idler sprocket mounted at said other end of said bar. 

1. An elongated rigid cutter bar body comprising: a pair of one piece elongated channel members; retaining means extending between at least portions of said channel members to maintain said channel members in spaced relationship with respect to one another; continuously longitudinally extending oppositely outwardly facing slots in respective outer sides of said channel members; and said slots being adapted to releasably retain a mounting portion of a chain guide member therein.
 2. A cutter bar body as specified in claim 1 wherein said spaced relationship of said channel members is convergently tapering towards only one end thereof to form a tapering bar body.
 3. A cutter bar incorporating a cutter bar body as specified in claim 1 wherein the taper of said tapered body matches the difference in size between a drive sprocket mounted at one end oF said body and a smaller idler sprocket mounted at the other end of said body.
 4. A cutter bar as specified in claim 3 wherein said drive sprocket has six teeth and said idler sprocket has five teeth.
 5. A cutter bar incorporating a cutter bar body as specified in claim 1 having chain guide assemblies at each side of said cutter bar body, each of said chain guide assemblies consisting of two guide members each including a pair of laterally spaced oppositely extending elongated portions with corresponding ones of said elongated portions being closely received within the one of said slots cooperative therewith, and means extending across said slots and through said ones of said elongated portions respectively to rigidly support said guide members with respect to said cutter bar body.
 6. A cutter bar as specified in claim 5 wherein said paired guide members are longitudinally offset so that gaps between guide members along one side of a portion of said cutter bar body are longitudinally spaced from gaps between guide members along the other side of said portion of said cutter bar body.
 7. A cutter bar as specified in claim 5 wherein the proximate guide surfaces of said guide assemblies on opposite sides of said bar are separated at one end of said bar by a distance substantially equal to the diameter of the inner tooth rot circle of a drive sprocket mounted at one end of said bar and said proximate guide surfaces at the other end of said bar are separated by a distance substantially less than said diameter.
 8. A cutter bar as specified in claim 7 comprising a nose shoe at said other end of said bar, said nose shoe providing an arcuate guide surface having a nose radius substantially less than one half the distance between said proximate guide surfaces at said other end.
 9. A cutter bar as specified in claim 7 wherein said distance substantially less than said drive sprocket diameter is substantially equal to the diameter of the inner tooth root circle of an idler sprocket mounted at said other end of said bar. 